Various medical procedures require that one or more fluids be injected into the patient. Medical imaging procedures oftentimes involve the injection of contrast media into the patient, possibly along with saline or other fluids, Other medical procedures involve injecting one or more fluids into a patient for therapeutic purposes. Power injectors may be used for these types of applications.
A power injector generally includes what is commonly referred to as a powerhead. One or more syringes may be mounted to the powerhead in various manners (e.g., detachably; rear-loading; front-loading; side-loading). Each syringe typically includes what may be characterized as a syringe plunger, piston, or the like. Each such syringe plunger is appropriately interconnected with an appropriate syringe plunger driver that is incorporated into the powerhead, such that operation of the syringe plunger driver axially advances the associated syringe plunger. One typical syringe plunger driver is in the form of a ram that is mounted on a threaded lead or drive screw. Rotation of the drive screw in one rotational direction advances the associated ram in one axial direction, while rotation of the drive screw in the opposite rotational direction advances the associated ram in the opposite axial direction.
Sometimes during contrast-enhanced imaging procedures, a dual-syringe power injector is used. One syringe may contain contrast media (e.g., iodine or gadolinium solutions) and the other syringe may contain a flushing solution (e.g., saline). In order to increase the likelihood that the contents of both syringes have been completely injected, the power injector may be configured to advance its rams far enough to slightly compress both syringe plungers into the end limits of the respective syringe barrels. If the residual compression force is high enough, it can hinder the manual removal of the syringes by the user, and whether the power injector is of a side load or a front load configuration. When hindered in this manner, users have been known to first manually retract both rams individually a slight amount to remove the compression forces, before disconnecting the syringes from the power injector.
Dual-syringe power injectors that incorporate an automatic ram retraction feature are also known. In one known configuration, the automatic ram retraction feature is configured to retract the rams sequentially. In this case, the user must wait for the first ram to be completely retracted and for the second ram to begin its retraction before the compression force has been removed from the both syringes. This wait period can typically be from 10 to 25 seconds. This waiting period is considered to be an annoyance by at least some users, as neither of the syringes is typically removed until both rams have been retracted to at least some degree in accordance with the foregoing.